QT prolongation in patients with index evaluation for seizure or epilepsy is predictive of all-cause mortality

BACKGROUND Refractory epilepsy confers a considerable lifetime risk of sudden unexplained death in epilepsy (SUDEP). Mechanisms may overlap with sudden cardiac death (SCD), particularly regarding QTc prolongation. Guidelines in the United States do not mandate the use of electrocardiography (ECG) in diagnostic evaluation of seizures or epilepsy. OBJECTIVE The purpose of this study was to determine the frequency of ECG use and of QT prolongation, and whether QT prolongation predicts mortality in patients with seizures. METHODS We performed a retrospective cohort study including all patients seen at Mayo Clinic in Rochester, Minnesota, from January 1, 2000, to July 31, 2015, with index evaluation for seizure or epilepsy. Patients with an ECG were categorized by the presence of a prolonged QT interval with a primary endpoint of all-cause mortality after the 15-year observation period. RESULTS Optimal cutoff QT intervals most predictive of mortality were identified. Median age was 40.0 years. An ECG was obtained in 18,222 patients (57.4%). After patients with confounding ECG findings were excluded, primary prolonged QT intervals were seen in 223 cases (1.4%), similar to the general population. Kaplan-Meier analysis demonstrated a significant increase in mortality (Cox hazard ratio [HR] 1.90; 95% confidence interval [CI] 1.76-2.05) for prolonged optimal cutoff QT, maintained after adjustments for age, Charlson comorbidity index, and sex (HR 1.48; 95% CI 1.37-1.59). CONCLUSION Use of ECG in diagnostic workup of patients with seizures is poor. A prolonged optimal cutoff QTc interval predicts all-cause mortality in patients evaluated for seizure and those diagnosed with epilepsy. We advocate the routine use of a 12-lead ECG at index evaluation in patients with seizure or epilepsy.